/* Lesson 17-1 */
 /*    File Name = les1701.sas   10/18/01   */

options linesize=79 pagesize=20;

data air;
  infile 'usair2.prn';
  input id $ y x1 x2 x3 x4 x5 x6;
/*
  label id='Cities in US'
         y='SO2 of air in micrograms per cubic metre'
        x1='Average annual temperature in F'
        x2='Number of manufacturing enterprises employing 20 or more workers'
        x3='Population size (1970 census); in thousands'
        x4='Average annual wind speed in miles per hour'
        x5='Average annual precipitation in inches'
        x6='Average number of days with precipitation per year'
;
*/

proc print data=air(obs=10);
run;

proc corr data=air;
run;

proc reg data=air;
  model y=x1 x2 x3 x4 x5 x6;
  output out=outreg1 predicted=pred1 residual=resid1;
run;

proc plot data=outreg1;
  plot resid1*pred1;
  plot resid1*x1;
  plot resid1*x2;
  plot resid1*x3;
  plot resid1*x4;
  plot resid1*x5;
  plot resid1*x6;
  plot resid1*y;
run;

proc reg data=air;
  model y=x1-x6 / selection=stepwise;
  output out=outreg2 predicted=pred2 residual=resid2;
run;

proc print data=outreg2(obs=15);
run;

proc plot data=outreg2;
  plot resid2*pred2;
  plot resid2*(x1 x2 x3 x4 x5 x6);
  plot resid2*(x1-x6);
  plot resid2*y;
run;

proc reg data=air;
  model y=x1-x6 / selection=rsquare;
run;